The present invention relates to a constant temperature coolant circulating apparatus for supplying a constant temperature coolant to a heat load in a circulating manner to cool the heat load.
As this type of a constant temperature coolant circulating apparatus, there is a known apparatus formed of a coolant circuit for supplying a coolant to a heat load in a circulating manner, a refrigerating circuit for cooling the coolant a temperature of which has increased by cooling the heat load by exchanging heat with refrigerant in a heat exchanger, and a control portion for controlling these circuits, for example.
The coolant circuit has a tank in which the coolant is accommodated and the coolant in the tank is supplied to the heat load by a pump. After the coolant a temperature of which has increased by cooling the heat load flows back to the heat exchanger in the refrigerating circuit and is cooled, the coolant flows into the tank and is supplied to the load again.
The heat load is normally connected to such a circulating apparatus through outside pipes prepared by a user. However, the kind of heat load, a heat capacity, and a place at which the apparatus is installed are not necessarily fixed but are diversely different depending on the user. Therefore, the outside pipes are extremely long and have large capacities or are risers and in higher positions than the circulating apparatus in some cases, which is liable to cause a problem of backflow of the coolant in the outside pipes into the circulating apparatus and overflowing of the coolant from the tank when operation of the apparatus is stopped. If the low-temperature coolant is kept encapsulated in the outside pipes when operation is stopped, volume of the coolant increases due to increase of the temperature of the coolant to a room temperature and pressure in the outside pipes may become abnormally high pressure- to break the pipes. Furthermore, in maintenance and inspections of the outside pipes and the load, it is required to safely and reliably discharge and recover the coolant in the outside pipes by a simple method.
It is a main technical object of the invention to provide a constant temperature coolant circulating apparatus which can solve all of the problems of the above-described prior-art apparatus and has excellent safety.
To achieve the above object, in a circulating apparatus of the present invention, a check valve for preventing backflow of a coolant in an outside pipe into the circulating apparatus when operation is. stopped and a cubical expansion relief valve which opens to let a part of the coolant flow back to the circulating apparatus when pressure of the coolant in the outside pipe increases excessively are connected in parallel to each other and a purge check valve for blowing compressed gas into the outside pipe in recovering the coolant in the outside pipe is connected in a primary-side flow path for sending the coolant to a heat load through the outside pipe.
In such a circulating apparatus of the invention, when operation of the apparatus is stopped, backflow of the coolant in the outside pipe can be prevented by operation of the check valve. Besides, even if volume of the coolant increases due to a temperature rise of the coolant encapsulated in the outside pipe and internal pressure of the outside pipe increases, a part of the coolant flows back to the circulating apparatus by operation of the cubical expansion relief valve before the internal pressure becomes abnormally high pressure and breakage of the outside pipe is prevented. In maintenance and inspections of the outside pipe and the load, by blowing compressed gas into the outside pipe through the purge check valve, the coolant in the outside pipe can be discharged and recovered safely and reliably by a simple method.
In the invention, it is preferable that a flow rate control valve for controlling a flow rate or pressure of the circulating coolant is connected in the secondary-side flow path of the circulating apparatus, a recovering port for recovering the coolant in the outside pipe in another vessel is provided in a position closer to an outside pipe connecting hole than a position in which the flow rate control valve is connected, a bypass flow path connecting the secondary-side flow path and the primary-side flow path is provided between both the flow paths, and a bypass flow rate control valve which opens to let a part of the coolant in the primary-side flow path flow into the secondary-side flow path when the pressure of the coolant in the outside pipe exceeds prescribed pressure during operation is connected in the bypass flow path.
As a result, the flow rate or pressure of the coolant can be controlled by the flow rate control valve according to a capacity of the heat load. Besides, in recovering the coolant in the outside pipe, if it is necessary to recover the coolant in another vessel without causing the coolant to flow back to the tank of the circulating apparatus, the flow rate adjusting valve is closed and the recovering port is opened to thereby recover the coolant in another vessel through the recovering port. When the pressure of the coolant in the outside pipe exceeds the prescribed pressure, it is possible to relieve the pressure to the secondary side through the bypass flow path and the bypass flow rate control valve to thereby further improve safety.
According to a preferable concrete embodiment of the invention, a combination valve unit is formed by integrally connecting a supply junction pipe and a return junction pipe which form parts of the primary-side flow path and the secondary-side flow path, the check valve, the cubical expansion relief valve, the purge check valve, the flow rate control valve, the recovering port, the bypass flow path, and the bypass flow rate control valve, a primary-side main pipe connecting hole and a secondary-side main pipe connecting hole which can be detachably connected to a supply main pipe and a return main pipe of the circulating apparatus and a pipe connecting hole to which the outside pipe can be detachably connected are provided to the combination valve unit, and the heat load is connected to the circulating apparatus through the combination valve unit.